How to get a count of first elements and sum of second element in a list of tuples in python?

Question

I have a list of tuples and I am expecting a dictionary where I want to count number of times the first element is repeated and sum of all the second elements.

For eg :-

input_list = [('Skills', 3), ('Wholesome', 3), ('FanArt', 3), ('Clip', 3), ('Skills', 2), ('FanArt', 2)]

Expected Output :

{"Skills": 5, "Wholesome": 3, "FanArt": 5, "Clip": 3}

I am expecting a optimised way to do this

I have tried it with simple programming with for loops. But I want to use itertools or some built in package.

Answer 1

You can use this

input_list = [('Skills', 3), ('Wholesome', 3), ('FanArt', 3), ('Clip', 3), ('Skills', 2), ('FanArt', 2)]


output_dict = {}
# Looping over tuple value
for k, v in input_list:
    if (k in output_dict): # if key exists then add value
        output_dict[k] += v
    else:
        output_dict[k] = v # if key not exists then key:value
print(output_dict)

---

You can also use the default list

from collections import defaultdict

input_list = [('Skills', 3), ('Wholesome', 3), ('FanArt', 3), ('Clip', 3), ('Skills', 2), ('FanArt', 2)]
output_dict = defaultdict(int)


for key, value in input_list:
    output_dict[key] += value

print(dict(output_dict))

---

Counter from collections will also work same as above

from collections import Counter

input_list = [('Skills', 3), ('Wholesome', 3), ('FanArt', 3), ('Clip', 3), ('Skills', 2), ('FanArt', 2)]

output_dict = Counter()

for key, value in input_list:
    output_dict[key] += value

print(dict(output_dict))

Output

{'Skills': 5, 'Wholesome': 3, 'FanArt': 5, 'Clip': 3} # for all above code